Self-erecting folding fin



Sept. 20, 1966 s. KONGELBECK 3,273,500

SELF-ERECTING FOLDING FIN Filed Jan. 25, 1965 2 SheetsSheet 1 22 SVERRE KONGELBECK INVENTOR- gzdaxmiaw ATTORNEY Sept. 20,- 1966 s. KONGELBECK SELF-ERECTING FOLDING FIN 2 Sheets-Sheet 2 Filed Jan. 25, 1965 5VERRE KONGELBECK INVENTOR.

ATTORNEY United States Patent 3,273,500 SELF-ERECTING FOLDING FIN Sverre Kongelbeck, Silver Spring, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed Jan. 25, 1965, Ser. No. 427,995 3 Claims. (Cl. 10250) The present invention relates generally to fins for aerial missiles, and more particularly to a self-erecting folding fin that is latched in a folded position prior to missile launching but which springs into an erect position after the missile is launched.

Missiles and rockets are by necessity fitted with fins or wings for stabilizing and controlling their flight through the atmosphere. These fins, unless removed or collapsed during storage, require an increase in the amount of space necessary for storage by a factor of two or three. Several folding fin structures have been proposed, among them being the folding fin disclosed in U.S. Patent No. 2,925,- 966, S. K-ongelbeck, inventor, assigned to the same assignee as the present invention. The folding fin shown in the referenced patent may be erected by hand or by any mechanism capable of applying an external force to the fin. While the referenced folding fin solves the problem of minimized storage space, its use results in a delay during the launch cycle, because of the time required to erect it.

The provision of a self-erecting mechanism, built into the fin or wing of a supersonic vehicle, is complicated by the fact that supersonic airfoils are necessarily thin structures which are subjected to unusually high panel loads. Further, any self-erecting mechanism has to be contained within the airfoil since projecting hinges, latches, or springs would spoil the air flow over the aerodynamic surfaces, thereby inducing excessive drag and friction.

It is, therefore, one object of this invention to provide a self-erecting, =fo-ldable fin for an aerial missile.

Another object of the invention is to provide a fin which erects automatically and latches into erect position.

Still another object of the present invention is to provide a fin which is substantially free of protruding surfaces or mechanisms.

A further object of the invention is to provide a mechanism for initially latching the missile fins in a retracted position and releasing them automatically upon launching of the missile.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a perspective view of the aft section of an aerial missile, showing four self-erecting fins in erect positions;

FIG. 2 is an end elevation of the missile, showing the fins latched in their folded positions;

FIG. 3 is a detail section on the line 33 of FIG. 2, showing the latch mechanism engaging a pair of fins in their folded positions, a portion of the launch tube containing the missile being shown in broken lines;

FIG. 4 is a perspective view of a single self-erecting fin, cut away to show its latch and spring mechanism; .and

FIG. 5 is an enlarged detail perspective view illustrating the locking mechanism of the present invention in an unlocked or folded position.

The self-erecting folding fins of the instant invention each include a base portion and a body portion hingedly connected by a pair of pins which pass through a mounting spar extending from said base portion into said body portion. The pair of hinge pins includes a latch release pin and a spring mounting pin. A torsion spring, which erects the self-erecting fin, extends back firom said spring mounting pin through a spring housing and terminates at the trailing edge of the fins body portion. The latch release pin, upon erection of the self-erecting fin, allows a spring-loaded latch pin in the center of the mounting spar to extend into a latch port in the body portion, thereby latching said body portion in an erect position. The body portion of each fin has a slot parallel to its center axis, through which a latch mechanism passes to initially secure an adjacent pair of fins in their folded positions.

Referring now to the drawings, FIG. 1 shows the aft section 10 of an aerial missile with tour self-erecting fins 12, 14, 16, and 18 in their erect positions. Each fin includes a base portion 20 which is pivotally attached to the missile It) by a mounting spa-r 22 that passes through the center of said base portion. The mounting spars 22 are equally spaced about the periphery of the missile with the axis of each spar perpendicular to the longitudinal axis of the missile. A body portion 24 completes the aerodynamic surface of each fin and is hingedly attached to the mounting spar 22 by pin means, to be hereinafter described. The fins are shown in FIG. 2 in their folded positions with pre-launch latch mechanisms 26 holding companion pairs retracted against the urging of a spring, also to be described hereinafter.

A slot 28 is formed in the body portion 24 of each of the fins 12, 14, 16 and 18, medially of its width and near its outer end. The slots are so arranged that when the body portions of companion fins, say the fins 14 and 16 and 12 and 18, are caused to overlap in retracted positions, as shown in FIG. 2, said slots will be brought into registry. As Will be seen, one of the prelaunch latch mechanisms 26 is required for each companion pair of fins, and each said mechanism 26 includes a shear bolt 30 having a threaded outer end portion on which is secured an impact nut 32. As seen in FIG. 3, the bolt 30 is relieved by a groove 34 that will determine the point at which said bolt Will shear, when shearing force is applied thereto, as will be described hereinafter. The impact nut 32 is constructed of a plastic shock absorbing material with a threaded metal insert 36 which receives said shear bolt 31), and a washer 38 is placed between the impact nut 32 and the body portion 24 of the fin. The portion of the launch tube or platform shown at 40 includes a bracket 42 that extends into the path of the shear bolt 26 so that when a missile moves forward during a launching operation, the bolt will contact said bracket and be broken off at the groove 34. The fins secured by latch mechanism 26 will thus be freed and will erect themselves as the missile clears the launch tube, by mechanism now to be described. As Wlllnbfi obvious, a latch mechanism 26 is used for holding retracted a similar pair of diametrically opposite fins, and the shear bolt of this mechanism is broken by contact with a bracket similar to the bracket 42 as the missile is launched.

In FIG. 4 the details of construction of the self-erecting 7 fin are illustrated. The four self-erecting fins, save for the directions in which they fold, are constructed in an identical manner, and hence only one fin will herein be described. The base portion 20 with its mounting spar 22 along with its associated body portion 24, is shown removed from the missile and in a retracted position. The base portion 20 includes said mounting spar 22 and oppositely extending tongues 43 and 43'. The cylindrical mounting spar 22, which forms the rotational axis of the fin, extends beyond the fin's base portion 20 to form a housing 44 whose shape is generally rectangular. Said mounting spar housing is longitudinally bored at 46, along its center axis and from its upper end, to receive a latch pin 48, and is transversely bored at 50, parallel with the plane of the fin, to receive a latch release pin 52 on the forward side and a spring mounting pin 54 on the aft side. A pair of positive stops 56 extend from the upper end of the mounting spar housing 44 at the forward and aft side corners thereof and engage in a pair of recesses 57 in the body portion 24 when the fin is in erect position to provide proper support for said body portion. A slot 58 passes through the mounting spar housing 44 and the latch pin 48 perpendicular to the bored passageways 46 and 50. A tool, not shown, may be inserted to retract the latch pin 48, for a purpose to be described hereinafter.

As seen in FIG. 5, the latch pin 48 is loaded by a pair of compression springs 60 and 62 so as to be forced upward along the axis of the mounting spar 22. The body portion 24 swings about an axis transverse to the rotational axis of the mounting spar 22 on the pair of cylindrical hinge pins 52 and 54. Latch release pin 52, in the forward position, is rabbeted at its inner end to provide an axially extending flat surface 64. An upper center portion 66, on the forward side of the latch pin 48, is milled flat across its entire width. A lower center portion 68 is milled flat only across half the diameter of the latch pin 48, thereby providing a detent shoulder 70 and a flat vertical clearance surface 72.

As will be readily understood, in the retracted condition (FIG. 4), the detent shoulder 70 bears on the outer surface of the latch release pin 52 and holds the latch pin 48 securely against the expansive force of springs 60 and 62. Upon movement of the body portion 24 to an upright or erect condition the rounded surface of the latch release pin 52 runs off the detent shoulder 70, permitting the clearance surface 72 to pass the surface 64 of said latch release pin. The latch pin 48 is then free to be driven upward by the springs 60 and 62. The latch pin 48 thus extends into a keeper 74 in the body portion 24. The latch pin 48 is beveled at 76 to permit easy movement of said pin toward the keeper as the body portion is moved to full erect position.

The hinge pins 52 and 54 are permanently afl'ixed by roll pins 78. That is, the latch release pin 52 is pinned into the body portion 24 by one of said pins 78 While the spring mounting pin 54 is pinned into the mounting spar 22 by the other said pin 78. As shown at 80, the latch pin 48, on its aft side, is milled fiat across its entire width on both its upper center and lower center portions. This flat portion 80 provides a clearance for the inner end of the spring mounting pin 54. A bearing 82 mounts on :he spring mounting pin 54. Said bearings inner race is in tight fitting engagement with the spring mounting pin 52 while its outer race provides the pivotal support for :he aft section of the body portion 24.

Extending aft from the bearing 82 said spring mountn-g pin 54 terminates at a collar 84 which mounts the "orward end of a torsion spring 86. A tubular spring lousing 88 surrounds said spring 86 and extends from the :earing 82 aft to the trailing edge of the body portion 24. The outer race of the bearing 82 mounts in tight itting relation with the inner surface of said housing 88 ilong its forwardmost end. The aft end of the spring rousing 88 is closed by a coaxially arranged spring nounting plug 90 and socket 92. The torsion spring 86 s swaged at each end to form flats 94 through which pins '6 permanently connect said spring to the collar 84 and o the spring mounting plug 90.

The spring mounting socket 92 is pinned to the spring rousing 88 by a pair of roll pins 98. The torque of torion spring 86 is then adjusted by rotating the spring nounting plug 90 within said socket 92 until the desired orque is obtained. Once the spring is wound to its roper torque a roll pin 100 is inserted between the pring mounting plug 90 and socket 92, thereby oomleting the assembly.

In operation, the self-erecting fins are folded against is urging of springs 86 into an overlapping position and eld there by the prelaunch latch mechanisms 26. As fie missile is fired from its launch tube or platform 40 the angle brackets 42 come into contact with the impact nuts 32, thereby shearing the shear bolts 30 and releasing the self-erecting fins. Once released, the body portions 24 erect under the torque supplied by the springs 86. The latch release pins 54 pivot with the body portion and release the spring loaded latch pins 48 which extend into the keepers 74 in the erected body portions 24, thereby locking the fins in erect positions.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A self-erecting structure, comprising,

a spar,

a first hinge pin means rigidly connected to said spar and extending with its longitudinal axis perpendicular to the longitudinal axis of said spar,

said first hinge pin means having a collar at one end thereof,

a bearing mounted on said hinge pin means,

an erectable member mounted on said spar and being pivotable about the longitudinal axis of said first hinge pin means from a folded position to an erected position on said spar,

an aerodynamically smooth housing on said member covering said bearing, said hinge pin means, and said collar,

plug means covering one end of said housing,

torsion spring means within said housing and connected at one end to said plug, and at its other end to said collar, said torsion spring means urging said member into said erected position,

latch pin means slidably mounted within said spar along its longitudinal axis,

spring means mounted in said spar for urging said latch pin means into said erectable member when said member is pivoted to said erected position, and

a second hinge pin means attached to said erectable member and extending perpendicular to the longitudinal axis of said spar, said erectable member being pivotable about the longitudinal axis of said second hinge pin means,

said second hinge pin means engaging said latch pin means to restrain said latch pin means against the urging of said spring means until said erectable member is pivoted to said erected position.

2. A self-erecting structure as claimed in claim 1,

wherein said plug means is adjustable for regulating the tension of said torsion spring means.

3. A self-erecting structure as claimed in claim 2, having additionally a prelaunch latch mechanism for retaining said fin in a retracted position prior to launch from a vehicle launching mechanism, comprising a shear bolt formed with a groove therein and passing through said structure, and

an impact nut threadably attached to said bolt.

References Cited by the Examiner UNITED STATES PATENTS References (Iited by the Applicant UNITED STATES PATENTS 2,858,765 11/1958 Startzell.

BENJAMIN A. BORCHELT, Primary Examiner. V. R. PENDEGRASS, Assistant Examiner. 

1. A SELF-ERECTING STRUCTURE, COMPRISING, A SPAR, A FIRST HINGE PIN MEANS RIGIDLY CONNECTED TO SAID PAIR AND EXTENDING WITH ITS LONGITUDINAL AXIS PERPENDICULAR TO THE LONGITUDINAL AXIS OF SAID SPAR, SAID FIRST HINGE PIN MEANS HAVING A COLLAR AT ONE END THEREOF, A BEARING MOUNTED ON SAID HINGE PIN MEANS, AN ERECTABLE MEMBER MOUNTED ON SAID SPAR AND BEING PIVOTABLE ABOUT THE LONGITUDINAL AXIS OF SAID FIRST HINGE PIN MEANS FROM A FOLDED POSITION TO AN ERECTED POSITION ON SAID SPAR, AN AERODYNAMICALLY SMOOTH HOUSING ON SAID MEMBER COVERING SAID BEARING, SAID HINGER PIN MEANS, AND SAID COLLAR, PLUG MEANS COVERING ONE END OF SAID HOUSING, TORSION SPRING MEANS WITHIN SAID HOUSING AND CONNECTED AT ONE END TO SAID PLUG, AND AT ITS OTHER END TO SAID COLLAR, SAID TORSION SPRING MEANS URGING SAID MEMBER INTO SAID ERECTED POSITION, LATCH PIN MEANS SLIDABLY MOUNTED WITHIN SAID SPAR ALONG ITS LONGITUDINAL AXIS, SPRING MEANS MOUNTED IN SAID SPAR FOR URGING SAID LATCH PIN MEANS INTO SAID ERECTABLE MEMBER WHEN SAID MEMBER IS PIVOTED TO SAID ERECTED POSITION, AND A SECOND HINGE PIN MEANS ATTACHED TO SAID ERECTABLE MEMBER AND EXTENDING PERPENDICULAR TO THE LONGITUDINAL AXIS OF SAID SPAR, SAID ERECTABLE MEMBER BEING PIVOTABLE ABOUT THE LONGITUDINAL AXES OF SAID SECOND HINGE PIN MEANS, SAID SECOND HINGE PIN MEANS ENGAGING SAID LATCH PIN MEANS TO RESTRAIN SAID LATCH PIN M EANS AGAINST THE URGING OF SAID SPRING MEANS UNTIL SAID ERECTABLE MEMBER IS PIVOTED TO SAID ERECTED POSITION. 